Mercury switch



Aug- 5, -1952 N. slssENwlNE ETAL L 2,606,255

MERCURY SWITCH Filed oct. 5, 1949 L Qfm/ A @51j IN VEN TORJ /VORMANNr.rENwM/e .JACK FAn-KIN Arrom Patented ug. 5, 1952 2,606,256 MERCURYSWITCH Norman. Sissenwine, Takoma" Park; and JackV Ratzkin, Greenbelt,Md.

Application ootobor 5, 1949', soriai'Nofiisv'iz- (Grantedundor the aotof March- 3, 1883, as amonaoa April so, 192e; 370 o, G; 757) Claims.

The invention described herein, if patented, may be manufactured andused by or for the Government for governmental purposes, without thepayment to us of any royalty thereon.

This application is a continuation-in-part of our copending applicationSerial No. 78,264-, led February 24, 1949, now abandoned, for a MercurySwitch. n

This invention relates toY mercury switches; and while illustrated inconnection with a multipleI cam and primary circuit, such as commonlyused in' ignition systems of internal combustion engines, is capable ofgeneral use. Y

An object of the invention resides intheprovision of al switch whichwill eliminate the possibility of pitting and corrosion such asv causefreduent replacement when tungsten breaker points areA used.

nother object of' the invention" consists in providing aswito'hsu'ohthat the tim-fhg is autornatically maintainedl and changesinv temperature have no deleterious'- effects.

A furtherV object of the invention resides in the provision of a switchin which the contactsl are inclosed and so arranged asto eliminate thepossibility of arcing.

Another object of thev invention consists in providing a switch in whichther make or break is` caused by contacting.YY orseparating two chargesof mercury.

A still further object of thel invention consists in providing animproved ignition system' for internal combustion enginea Other objectsand advantages' of theh invention will beI apparent from the followingdescription when taken in connection with the' accompanying. drawings,in which', o

.Figure 1 is a perspective view of the switch associatedr with amultiple operating cam.v

Figure 2 is a longitudinal sectional view through the switch.

Figure 3f is a transverse sectional View taken ort line 3^3 of Figure2'; and

Figure' 4- is a vertical sectional view through a slightly modiedconstruction of a switchin closedv position'.

Figure 5 is asimilar view showing a stillfurther modi'ed-form ofswitch;Y and- Figure 6 is a planview of one of-` the switchesplacedinanl otherw-isef conventional ignition lcir- Cuit? Referring toAthe d"rawin'gsj`- in greater' detail, and particularly to Figures Ito3`i1'i'c1usiv'e, the numeral l indicates a block ofyinsulating'-iaterial, preferably formed' of glass or' sifil'ar Inarteri'al' which Wlht bet Wtted by -iu1-..= .T3 block otmate'rial forms`the body of thesw bore 2, with whichv c'rnr'nunicates atran'sverextending annularl recess`- or pocket 3, mo clearly shown Figure 3wher-ein one portiony of the pocket is shbwn asei'tendingf to av pointadjacent the upper wall of the" body meiiib and providedwith a' fillingopening 4.; p

Stlidably mounted 4with the borfe; 2V isv a pllii'figfr,` 5 formed offiberor other insulating material and having a metal conductor 6embedded' there'- in and extending axially thereof. The,fdiicitor E hasWelded theretoV ord integrally' formed therewith intermediate" its'ends, a metal'. dis'o 1 having ,al diameter corresponding to' thedialne-` tor of thenher 4member 5', and hei''g expd at! thevvperiphery"thereof. Thel nietal c'dctrrli extends beyond the end of the plunger 5',as in"- dicated by the numeral 8, and is surroundedby one end' vof acoilv yspring 9,- which" engages" the plunger Eat'on'e' end and: is"seated upon tleina ner faceV of a bracket l0' at its otherA end..'Iflfs` bracket is of general U`1s`hape c'nstfru' fon and' is providedwith outwardly-turned' flanges 'U means of which itrmayho secured toith'Body stationary portion l ofthe switch; The. to; is also prin/iden1 witha flange |2 which) bensoldered or otherwise electrically' conneV withone'terminal l3', ofthe primary' circuit in which; the switch-ismounted- AA oat Whisker connectedtotheiend` of conductor 6, and tbracket Ill,` Aservesf to' insure; a? ii'ow;y of elj t'zurrent-l throughthe circuit` when the; switi':l closed,

Disposed Within`- the annular pocket 3i ihthoy hodymomher l, tsjacharge-of mrourymi andthe filling opening 4, through vvl'iicli' the`pocket is? rohag'edl with mercury may' he 'closed by aV Yscrew l5,ywhich also" frs an; ancho" forr the othertermi"nall It'1 ofthe-Yprinaryci iti An air space Il,vr is provided above tle surface ofthe mercury for expansionprb"`s,i annif/a'A vent l'is'also provided..This chargent-me Fury ofcourse,l as clearly shown in-Figuresi 2l anif3T; forms anV electrical connection betweerfterminal ItV and the disk 1,when thelatter isinvtlie'po sition indicated in these figures. Thecurrent will then flow through rod 6, cat whisker III', and bracket I tothe other terminal I3, of the primary circuit. It will be noted thatwhen the disk or contact 1, is moved to the right (Figure 2), againstthe pressure of spring 9, beyond the charge of mercury I4, the circuitwill be broken.

The mercury switch shown in Figure 4 is substantially the same as thatdescribed above, except that the metal conductor I9 which corresponds tothe conductorV 6 of the previously described form is provided with ametal disk 20, which is of lesser diameter than the disk lI, of Figures1 to 3 inclusive, and is therefore of less diameter than the plunger 5.Consequently, in this modified construction, an annular pocket 2I isformed in the plunger and this pocket is filled with mercury, as clearlyindicated in these two figures. This construction of switch has all ofthe advantages of that shown in Figures l to 3, but has the additionaladvantage that it presents less resistance due to the molecular cohesionof the two bodies of mercury. Also, there is no wear on the contactingelements, and there is no coeiiicientv of thermal expansion to becontended with in a construction wherein the contacts are formed of twobodies of mercury.

The mercury switch shown in Figure is substantially identical with thatshown in Figure 4,

except that in lieu of the metal conductor I9, a

tubular cavity I9 is provided in the plunger 5, and has extendingtherefrom a plurality of radial passages I9" communicating with theannular channel 2l. The tubular cavity, radial passages and annularchannel are lled with mercury, and the mercury in the annular channelserves as a contact in cooperating with the mercury in the annularpocket 3. After the mercury is placed in the cavity I9 etc., the samemay be sealed by a screw plug cat Whisker I0' serves to conduct thecurrent from the plug 20 to the bracket I0.

With this particular construction of switch in which the column ofmercury is substituted for the solid metal conductor I9danger of injurytothe plug 5, by reason of unequal expansion of the parts due totemperature changes, is eliminated.

The mercury switches as described above, and as `heretofore indicated,are mounted in primary circuits generally indicated by the numeral 22,and provided with a storage battery 23, condenser 24, and an inductioncoil 25, which latter is associated with a secondary circuit 26 in whichthe distributor and spark plugs of an internal combustion engine may beconnected. The plunger i, is intermittently reciprocated to open andclosed position by a rotatably mounted multiple cam 21, provided with 6lobes in the present instance for use in a 6-cylinder internalcombustion engine, the plunger being held in operative contact with thecam by means of the spring 9. In this connection, it is to be notedthatA when the plunger 5 is in engagement with the dwell portions of therotary cam Z'I, the contact disk I or mercury 2I is in contact with themercury charge I4, and when the high portions or lobes ofthe cam engagethe plunger, the latter is moved to the right (Figure 2) so as to breakthe primary circuit and induce a high potential in the secondary circuit26. Y

This particular construction of an annular contact such as the metaldisk 1, cooperating with the annularly arranged charge Vof mercury, or aplurality of mercury contacts, has many advan- The tages, not only in anignition device such as illustrated herein, but also in electricalswitches generally. Changes in temperature will have no effect on theoperation of the switch because the charge of mercury fills the contactspace at all times; also the contacts are entirely inclosed and thuseliminate arcing. Moreover, accurate timing is automatically maintainedat all times because the switch is caused to open at the exact instantthat the left hand edge of the disk I or the mercury rings 2| or 2|leave the right hand edge of the annular charge 3 of mercury.Furthermore, by means of lthis arrangement the use of breaker points andthe resultant pitting, disarrangement of timing, and replacement of thepoints, are avoided. Additionally, the switches shown in Figures 4 and5, by reason of the contact being formed of two charges of mercury. willprovide lessened resistance for the reason mentioned above, and willobviate any possibility of wear on the contacts, since the mercurycharges are automatically maintained at full capacity. Also there can beno possibility of binding between the movable parts, inasmuch as thecontacting elements are formed of pockets of liquid metal.

The term mercury employed herein and in the claims to designate theliquid conductor is to be construed as including any electricalconductor which is liquid at normal temperatures.

In accordance with the patent statutes, We have described what we nowdeem to be the preferred form of construction, but since various minorchanges may be made in structural details without departing from thespirit of the invention, it is intended that all such variations beincluded within the scope of the appended claims.

We claim:

1. In a mercury switch a. stationary portion, a reciprocable portionassociated therewith, one of said portions provided with an annularmercury-receiving pocket, an annular metal contact connected with theother portion for contacting the mercury in said pocket, and electricalconductors connected with said pocket and said annular contactrespectively.

2. A mercury switch comprising a stationary portion of insulatingmaterial provided with a bore opening into an annular mercury-receivingpocket, av plunger formed of insulating material reciprocably mounted inthe bore, said plunger provided with a longitudinal mercury-receivingcavity and an external annular groove communicating therewith.

3. A mercury switch comprising a stationary portion of insulatingmaterial provided with a bore opening into an annular mercury-receivingpocket, a plunger formed of insulating material reciprocably mounted inthe bore, said plunger provided with a longitudinal mercury-receivingcavity, and an external annular groove communicating therewith, andelectrical conductors associated with said pocket and said cavity.

4. A mercury switch comprising a stationary portion of insulatingmaterial provided with a bore opening into an annular mercury-receivingpocket, said stationary portion provided with an air space and a ventingpassage connecting said pocket with the atmosphere, a plunger formed ofinsulating material reciprocably mounted in the bore, and an annularcontact carried by the plunger for coacti'on with the mercury in saidpocket, and a conductor disposed axially of the plunger vand connectedwith said annular contact.

5. A mercury switch comprising a stationary 5 portion of insulatingmaterial provided with a bore opening into an annular mercury-receivingpocket, a plunger formed of insulating material reciprocably mounted inthe bore, an annular contact on said plunger for coaction with the 5mercury in said pocket, and a conductor mounted axially of the plungerand connected to said annular contact.

NORMAN SISSENWIN E. JACK RATZKIN.

REFERENCES CITED The following references are of record in the file ofthis patent:

6 UNITED STATES PA'IENTS Number Name Date Harper Nov. 26, 1895 HuttonApr. 7, 1903 McLean Dec. 29,l 1903 Freese June 7, 1904 Crist et al. Oct.8, 1912 Sigman Dec. 4, 1934 Paris Feb. 10, 1948

